diff --git a/doc/src/sgml/array.sgml b/doc/src/sgml/array.sgml
index 55e4085d0dddfd77226ae943270554e369cdbab2..3ed8ce9c04363f3fbea6e077bcbf815ca374f074 100644
--- a/doc/src/sgml/array.sgml
+++ b/doc/src/sgml/array.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.51 2006/05/09 23:12:54 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.52 2006/09/29 21:22:21 tgl Exp $ -->
 
 <sect1 id="arrays">
  <title>Arrays</title>
@@ -350,11 +350,12 @@ UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}'
  </para>
 
  <para>
-  A stored array value can be enlarged by assigning to an element adjacent to
-  those already present, or by assigning to a slice that is adjacent
-  to or overlaps the data already present.  For example, if array
-  <literal>myarray</> currently has 4 elements, it will have five
-  elements after an update that assigns to <literal>myarray[5]</>.
+  A stored array value can be enlarged by assigning to element(s) not already
+  present.  Any positions between those previously present and the newly
+  assigned element(s) will be filled with nulls.  For example, if array
+  <literal>myarray</> currently has 4 elements, it will have six
+  elements after an update that assigns to <literal>myarray[6]</>,
+  and <literal>myarray[5]</> will contain a null.
   Currently, enlargement in this fashion is only allowed for one-dimensional
   arrays, not multidimensional arrays.
  </para>
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 8b0c11c163dd5029dcd011acaa739896a598c0c8..dd1f1649fad01ac3d4ac7b69f02d83266ba9f660 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.131 2006/09/10 20:14:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.132 2006/09/29 21:22:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1925,8 +1925,9 @@ array_get_slice(ArrayType *array,
  *		  modified entry.  The original array object is not changed.
  *
  * For one-dimensional arrays only, we allow the array to be extended
- * by assigning to the position one above or one below the existing range.
- * (XXX we could be more flexible: perhaps allow NULL fill?)
+ * by assigning to a position outside the existing subscript range; any
+ * positions between the existing elements and the new one are set to NULLs.
+ * (XXX TODO: allow a corresponding behavior for multidimensional arrays)
  *
  * NOTE: For assignments, we throw an error for invalid subscripts etc,
  * rather than returning a NULL as the fetch operations do.
@@ -1949,17 +1950,18 @@ array_set(ArrayType *array,
 				lb[MAXDIM],
 				offset;
 	char	   *elt_ptr;
-	bool		extendbefore = false;
-	bool		extendafter = false;
 	bool		newhasnulls;
 	bits8	   *oldnullbitmap;
 	int			oldnitems,
+				newnitems,
 				olddatasize,
 				newsize,
 				olditemlen,
 				newitemlen,
 				overheadlen,
 				oldoverheadlen,
+				addedbefore,
+				addedafter,
 				lenbefore,
 				lenafter;
 
@@ -1972,12 +1974,12 @@ array_set(ArrayType *array,
 		if (nSubscripts != 1)
 			ereport(ERROR,
 					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-					 errmsg("invalid array subscripts")));
+					 errmsg("wrong number of array subscripts")));
 
 		if (indx[0] < 0 || indx[0] * elmlen >= arraytyplen)
 			ereport(ERROR,
 					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-					 errmsg("invalid array subscripts")));
+					 errmsg("array subscript out of range")));
 
 		if (isNull)
 			ereport(ERROR,
@@ -1994,7 +1996,7 @@ array_set(ArrayType *array,
 	if (nSubscripts <= 0 || nSubscripts > MAXDIM)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-				 errmsg("invalid array subscripts")));
+				 errmsg("wrong number of array subscripts")));
 
 	/* make sure item to be inserted is not toasted */
 	if (elmlen == -1 && !isNull)
@@ -2028,70 +2030,72 @@ array_set(ArrayType *array,
 	if (ndim != nSubscripts)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-				 errmsg("invalid array subscripts")));
+				 errmsg("wrong number of array subscripts")));
 
 	/* copy dim/lb since we may modify them */
 	memcpy(dim, ARR_DIMS(array), ndim * sizeof(int));
 	memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));
 
+	newhasnulls = (ARR_HASNULL(array) || isNull);
+	addedbefore = addedafter = 0;
+
 	/*
 	 * Check subscripts
 	 */
-	for (i = 0; i < ndim; i++)
+	if (ndim == 1)
 	{
-		if (indx[i] < lb[i])
+		if (indx[0] < lb[0])
 		{
-			if (ndim == 1 && indx[i] == lb[i] - 1)
-			{
-				dim[i]++;
-				lb[i]--;
-				extendbefore = true;
-			}
-			else
-				ereport(ERROR,
-						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-						 errmsg("invalid array subscripts")));
+			addedbefore = lb[0] - indx[0];
+			dim[0] += addedbefore;
+			lb[0] = indx[0];
+			if (addedbefore > 1)
+				newhasnulls = true;				/* will insert nulls */
 		}
-		if (indx[i] >= (dim[i] + lb[i]))
+		if (indx[0] >= (dim[0] + lb[0]))
 		{
-			if (ndim == 1 && indx[i] == (dim[i] + lb[i]))
-			{
-				dim[i]++;
-				extendafter = true;
-			}
-			else
+			addedafter = indx[0] - (dim[0] + lb[0]) + 1;
+			dim[0] += addedafter;
+			if (addedafter > 1)
+				newhasnulls = true;				/* will insert nulls */
+		}
+	}
+	else
+	{
+		/*
+		 * XXX currently we do not support extending multi-dimensional
+		 * arrays during assignment
+		 */
+		for (i = 0; i < ndim; i++)
+		{
+			if (indx[i] < lb[i] ||
+				indx[i] >= (dim[i] + lb[i]))
 				ereport(ERROR,
 						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-						 errmsg("invalid array subscripts")));
+						 errmsg("array subscript out of range")));
 		}
 	}
 
 	/*
 	 * Compute sizes of items and areas to copy
 	 */
-	if (ARR_HASNULL(array) || isNull)
-	{
-		newhasnulls = true;
-		overheadlen = ARR_OVERHEAD_WITHNULLS(ndim,
-											 ArrayGetNItems(ndim, dim));
-	}
+	newnitems = ArrayGetNItems(ndim, dim);
+	if (newhasnulls)
+		overheadlen = ARR_OVERHEAD_WITHNULLS(ndim, newnitems);
 	else
-	{
-		newhasnulls = false;
 		overheadlen = ARR_OVERHEAD_NONULLS(ndim);
-	}
 	oldnitems = ArrayGetNItems(ndim, ARR_DIMS(array));
 	oldnullbitmap = ARR_NULLBITMAP(array);
 	oldoverheadlen = ARR_DATA_OFFSET(array);
 	olddatasize = ARR_SIZE(array) - oldoverheadlen;
-	if (extendbefore)
+	if (addedbefore)
 	{
 		offset = 0;
 		lenbefore = 0;
 		olditemlen = 0;
 		lenafter = olddatasize;
 	}
-	else if (extendafter)
+	else if (addedafter)
 	{
 		offset = oldnitems;
 		lenbefore = olddatasize;
@@ -2158,9 +2162,16 @@ array_set(ArrayType *array,
 	{
 		bits8	   *newnullbitmap = ARR_NULLBITMAP(newarray);
 
-		array_set_isnull(newnullbitmap, offset, isNull);
-		if (extendbefore)
-			array_bitmap_copy(newnullbitmap, 1,
+		/* Zero the bitmap to take care of marking inserted positions null */
+		MemSet(newnullbitmap, 0, (newnitems + 7) / 8);
+		/* Fix the inserted value */
+		if (addedafter)
+			array_set_isnull(newnullbitmap, newnitems - 1, isNull);
+		else
+			array_set_isnull(newnullbitmap, offset, isNull);
+		/* Fix the copied range(s) */
+		if (addedbefore)
+			array_bitmap_copy(newnullbitmap, addedbefore,
 							  oldnullbitmap, 0,
 							  oldnitems);
 		else
@@ -2168,7 +2179,7 @@ array_set(ArrayType *array,
 			array_bitmap_copy(newnullbitmap, 0,
 							  oldnullbitmap, 0,
 							  offset);
-			if (!extendafter)
+			if (addedafter == 0)
 				array_bitmap_copy(newnullbitmap, offset + 1,
 								  oldnullbitmap, offset + 1,
 								  oldnitems - offset - 1);
@@ -2202,6 +2213,11 @@ array_set(ArrayType *array,
  *		  A new array is returned, just like the old except for the
  *		  modified range.  The original array object is not changed.
  *
+ * For one-dimensional arrays only, we allow the array to be extended
+ * by assigning to positions outside the existing subscript range; any
+ * positions between the existing elements and the new ones are set to NULLs.
+ * (XXX TODO: allow a corresponding behavior for multidimensional arrays)
+ *
  * NOTE: we assume it is OK to scribble on the provided index arrays
  * lowerIndx[] and upperIndx[].  These are generally just temporaries.
  *
@@ -2235,6 +2251,8 @@ array_set_slice(ArrayType *array,
 				newitemsize,
 				overheadlen,
 				oldoverheadlen,
+				addedbefore,
+				addedafter,
 				lenbefore,
 				lenafter,
 				itemsbefore,
@@ -2298,55 +2316,70 @@ array_set_slice(ArrayType *array,
 	if (ndim < nSubscripts || ndim <= 0 || ndim > MAXDIM)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-				 errmsg("invalid array subscripts")));
+				 errmsg("wrong number of array subscripts")));
 
 	/* copy dim/lb since we may modify them */
 	memcpy(dim, ARR_DIMS(array), ndim * sizeof(int));
 	memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));
 
+	newhasnulls = (ARR_HASNULL(array) || ARR_HASNULL(srcArray));
+	addedbefore = addedafter = 0;
+
 	/*
-	 * Check provided subscripts.  A slice exceeding the current array limits
-	 * throws an error, *except* in the 1-D case where we will extend the
-	 * array as long as no hole is created. An empty slice is an error, too.
+	 * Check subscripts
 	 */
-	for (i = 0; i < nSubscripts; i++)
+	if (ndim == 1)
 	{
-		if (lowerIndx[i] > upperIndx[i])
+		Assert(nSubscripts == 1);
+		if (lowerIndx[0] > upperIndx[0])
 			ereport(ERROR,
 					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-					 errmsg("invalid array subscripts")));
-		if (lowerIndx[i] < lb[i])
+					 errmsg("upper bound cannot be less than lower bound")));
+		if (lowerIndx[0] < lb[0])
 		{
-			if (ndim == 1 && upperIndx[i] >= lb[i] - 1)
-			{
-				dim[i] += lb[i] - lowerIndx[i];
-				lb[i] = lowerIndx[i];
-			}
-			else
+			if (upperIndx[0] < lb[0] - 1)
+				newhasnulls = true;				/* will insert nulls */
+			addedbefore = lb[0] - lowerIndx[0];
+			dim[0] += addedbefore;
+			lb[0] = lowerIndx[0];
+		}
+		if (upperIndx[0] >= (dim[0] + lb[0]))
+		{
+			if (lowerIndx[0] > (dim[0] + lb[0]))
+				newhasnulls = true;				/* will insert nulls */
+			addedafter = upperIndx[0] - (dim[0] + lb[0]) + 1;
+			dim[0] += addedafter;
+		}
+	}
+	else
+	{
+		/*
+		 * XXX currently we do not support extending multi-dimensional
+		 * arrays during assignment
+		 */
+		for (i = 0; i < nSubscripts; i++)
+		{
+			if (lowerIndx[i] > upperIndx[i])
+				ereport(ERROR,
+						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+						 errmsg("upper bound cannot be less than lower bound")));
+			if (lowerIndx[i] < lb[i] ||
+				upperIndx[i] >= (dim[i] + lb[i]))
 				ereport(ERROR,
 						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-						 errmsg("invalid array subscripts")));
+						 errmsg("array subscript out of range")));
 		}
-		if (upperIndx[i] >= (dim[i] + lb[i]))
+		/* fill any missing subscript positions with full array range */
+		for (; i < ndim; i++)
 		{
-			if (ndim == 1 && lowerIndx[i] <= (dim[i] + lb[i]))
-				dim[i] = upperIndx[i] - lb[i] + 1;
-			else
+			lowerIndx[i] = lb[i];
+			upperIndx[i] = dim[i] + lb[i] - 1;
+			if (lowerIndx[i] > upperIndx[i])
 				ereport(ERROR,
 						(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-						 errmsg("invalid array subscripts")));
+						 errmsg("upper bound cannot be less than lower bound")));
 		}
 	}
-	/* fill any missing subscript positions with full array range */
-	for (; i < ndim; i++)
-	{
-		lowerIndx[i] = lb[i];
-		upperIndx[i] = dim[i] + lb[i] - 1;
-		if (lowerIndx[i] > upperIndx[i])
-			ereport(ERROR,
-					(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-					 errmsg("invalid array subscripts")));
-	}
 
 	/* Do this mainly to check for overflow */
 	nitems = ArrayGetNItems(ndim, dim);
@@ -2366,16 +2399,10 @@ array_set_slice(ArrayType *array,
 	 * Compute space occupied by new entries, space occupied by replaced
 	 * entries, and required space for new array.
 	 */
-	if (ARR_HASNULL(array) || ARR_HASNULL(srcArray))
-	{
-		newhasnulls = true;
+	if (newhasnulls)
 		overheadlen = ARR_OVERHEAD_WITHNULLS(ndim, nitems);
-	}
 	else
-	{
-		newhasnulls = false;
 		overheadlen = ARR_OVERHEAD_NONULLS(ndim);
-	}
 	newitemsize = array_nelems_size(ARR_DATA_PTR(srcArray), 0,
 									ARR_NULLBITMAP(srcArray), nsrcitems,
 									elmlen, elmbyval, elmalign);
@@ -2407,7 +2434,7 @@ array_set_slice(ArrayType *array,
 		char	   *oldarraydata = ARR_DATA_PTR(array);
 		bits8	   *oldarraybitmap = ARR_NULLBITMAP(array);
 
-		itemsbefore = slicelb - oldlb;
+		itemsbefore = Min(slicelb, oldub + 1) - oldlb;
 		lenbefore = array_nelems_size(oldarraydata, 0, oldarraybitmap,
 									  itemsbefore,
 									  elmlen, elmbyval, elmalign);
@@ -2467,13 +2494,15 @@ array_set_slice(ArrayType *array,
 			bits8	   *newnullbitmap = ARR_NULLBITMAP(newarray);
 			bits8	   *oldnullbitmap = ARR_NULLBITMAP(array);
 
-			array_bitmap_copy(newnullbitmap, 0,
+			/* Zero the bitmap to handle marking inserted positions null */
+			MemSet(newnullbitmap, 0, (nitems + 7) / 8);
+			array_bitmap_copy(newnullbitmap, addedbefore,
 							  oldnullbitmap, 0,
 							  itemsbefore);
-			array_bitmap_copy(newnullbitmap, itemsbefore,
+			array_bitmap_copy(newnullbitmap, lowerIndx[0] - lb[0],
 							  ARR_NULLBITMAP(srcArray), 0,
 							  nsrcitems);
-			array_bitmap_copy(newnullbitmap, itemsbefore + nsrcitems,
+			array_bitmap_copy(newnullbitmap, addedbefore + itemsbefore + nolditems,
 							  oldnullbitmap, itemsbefore + nolditems,
 							  itemsafter);
 		}
diff --git a/src/test/regress/expected/arrays.out b/src/test/regress/expected/arrays.out
index b0f9f69a57f0e908f07e7ed07c901c8707b8ce7c..643ae7f39bdfa638355c8aef2bd2d87ca9876775 100644
--- a/src/test/regress/expected/arrays.out
+++ b/src/test/regress/expected/arrays.out
@@ -143,6 +143,116 @@ SELECT a,b,c FROM arrtest;
  [4:4]={NULL}  | {3,4}                 | {foo,new_word}
 (3 rows)
 
+--
+-- test array extension
+--
+CREATE TEMP TABLE arrtest1 (i int[], t text[]);
+insert into arrtest1 values(array[1,2,null,4], array['one','two',null,'four']);
+select * from arrtest1;
+      i       |          t          
+--------------+---------------------
+ {1,2,NULL,4} | {one,two,NULL,four}
+(1 row)
+
+update arrtest1 set i[2] = 22, t[2] = 'twenty-two';
+select * from arrtest1;
+       i       |             t              
+---------------+----------------------------
+ {1,22,NULL,4} | {one,twenty-two,NULL,four}
+(1 row)
+
+update arrtest1 set i[5] = 5, t[5] = 'five';
+select * from arrtest1;
+        i        |                t                
+-----------------+---------------------------------
+ {1,22,NULL,4,5} | {one,twenty-two,NULL,four,five}
+(1 row)
+
+update arrtest1 set i[8] = 8, t[8] = 'eight';
+select * from arrtest1;
+              i              |                        t                        
+-----------------------------+-------------------------------------------------
+ {1,22,NULL,4,5,NULL,NULL,8} | {one,twenty-two,NULL,four,five,NULL,NULL,eight}
+(1 row)
+
+update arrtest1 set i[0] = 0, t[0] = 'zero';
+select * from arrtest1;
+                  i                  |                             t                              
+-------------------------------------+------------------------------------------------------------
+ [0:8]={0,1,22,NULL,4,5,NULL,NULL,8} | [0:8]={zero,one,twenty-two,NULL,four,five,NULL,NULL,eight}
+(1 row)
+
+update arrtest1 set i[-3] = -3, t[-3] = 'minus-three';
+select * from arrtest1;
+                         i                         |                                         t                                         
+---------------------------------------------------+-----------------------------------------------------------------------------------
+ [-3:8]={-3,NULL,NULL,0,1,22,NULL,4,5,NULL,NULL,8} | [-3:8]={minus-three,NULL,NULL,zero,one,twenty-two,NULL,four,five,NULL,NULL,eight}
+(1 row)
+
+update arrtest1 set i[0:2] = array[10,11,12], t[0:2] = array['ten','eleven','twelve'];
+select * from arrtest1;
+                          i                          |                                        t                                        
+-----------------------------------------------------+---------------------------------------------------------------------------------
+ [-3:8]={-3,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,8} | [-3:8]={minus-three,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,eight}
+(1 row)
+
+update arrtest1 set i[8:10] = array[18,null,20], t[8:10] = array['p18',null,'p20'];
+select * from arrtest1;
+                               i                               |                                            t                                            
+---------------------------------------------------------------+-----------------------------------------------------------------------------------------
+ [-3:10]={-3,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20} | [-3:10]={minus-three,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20}
+(1 row)
+
+update arrtest1 set i[11:12] = array[null,22], t[11:12] = array[null,'p22'];
+select * from arrtest1;
+                                   i                                   |                                                t                                                 
+-----------------------------------------------------------------------+--------------------------------------------------------------------------------------------------
+ [-3:12]={-3,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20,NULL,22} | [-3:12]={minus-three,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20,NULL,p22}
+(1 row)
+
+update arrtest1 set i[15:16] = array[null,26], t[15:16] = array[null,'p26'];
+select * from arrtest1;
+                                            i                                            |                                                          t                                                          
+-----------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------
+ [-3:16]={-3,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20,NULL,22,NULL,NULL,NULL,26} | [-3:16]={minus-three,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20,NULL,p22,NULL,NULL,NULL,p26}
+(1 row)
+
+update arrtest1 set i[-5:-3] = array[-15,-14,-13], t[-5:-3] = array['m15','m14','m13'];
+select * from arrtest1;
+                                                i                                                 |                                                          t                                                          
+--------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------
+ [-5:16]={-15,-14,-13,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20,NULL,22,NULL,NULL,NULL,26} | [-5:16]={m15,m14,m13,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20,NULL,p22,NULL,NULL,NULL,p26}
+(1 row)
+
+update arrtest1 set i[-7:-6] = array[-17,null], t[-7:-6] = array['m17',null];
+select * from arrtest1;
+                                                     i                                                     |                                                              t                                                               
+-----------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------
+ [-7:16]={-17,NULL,-15,-14,-13,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20,NULL,22,NULL,NULL,NULL,26} | [-7:16]={m17,NULL,m15,m14,m13,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20,NULL,p22,NULL,NULL,NULL,p26}
+(1 row)
+
+update arrtest1 set i[-12:-10] = array[-22,null,-20], t[-12:-10] = array['m22',null,'m20'];
+select * from arrtest1;
+                                                                 i                                                                 |                                                                          t                                                                           
+-----------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------
+ [-12:16]={-22,NULL,-20,NULL,NULL,-17,NULL,-15,-14,-13,NULL,NULL,10,11,12,NULL,4,5,NULL,NULL,18,NULL,20,NULL,22,NULL,NULL,NULL,26} | [-12:16]={m22,NULL,m20,NULL,NULL,m17,NULL,m15,m14,m13,NULL,NULL,ten,eleven,twelve,NULL,four,five,NULL,NULL,p18,NULL,p20,NULL,p22,NULL,NULL,NULL,p26}
+(1 row)
+
+delete from arrtest1;
+insert into arrtest1 values(array[1,2,null,4], array['one','two',null,'four']);
+select * from arrtest1;
+      i       |          t          
+--------------+---------------------
+ {1,2,NULL,4} | {one,two,NULL,four}
+(1 row)
+
+update arrtest1 set i[0:5] = array[0,1,2,null,4,5], t[0:5] = array['z','p1','p2',null,'p4','p5'];
+select * from arrtest1;
+           i            |             t              
+------------------------+----------------------------
+ [0:5]={0,1,2,NULL,4,5} | [0:5]={z,p1,p2,NULL,p4,p5}
+(1 row)
+
 --
 -- array expressions and operators
 --
diff --git a/src/test/regress/sql/arrays.sql b/src/test/regress/sql/arrays.sql
index ad5f455cf490e546d3d2b4fb765181ae7979daf5..1f574a018487711ea897aafd7fbd02a5b5769d36 100644
--- a/src/test/regress/sql/arrays.sql
+++ b/src/test/regress/sql/arrays.sql
@@ -90,6 +90,42 @@ SELECT a FROM arrtest WHERE a[2] IS NULL;
 DELETE FROM arrtest WHERE a[2] IS NULL AND b IS NULL;
 SELECT a,b,c FROM arrtest;
 
+--
+-- test array extension
+--
+CREATE TEMP TABLE arrtest1 (i int[], t text[]);
+insert into arrtest1 values(array[1,2,null,4], array['one','two',null,'four']);
+select * from arrtest1;
+update arrtest1 set i[2] = 22, t[2] = 'twenty-two';
+select * from arrtest1;
+update arrtest1 set i[5] = 5, t[5] = 'five';
+select * from arrtest1;
+update arrtest1 set i[8] = 8, t[8] = 'eight';
+select * from arrtest1;
+update arrtest1 set i[0] = 0, t[0] = 'zero';
+select * from arrtest1;
+update arrtest1 set i[-3] = -3, t[-3] = 'minus-three';
+select * from arrtest1;
+update arrtest1 set i[0:2] = array[10,11,12], t[0:2] = array['ten','eleven','twelve'];
+select * from arrtest1;
+update arrtest1 set i[8:10] = array[18,null,20], t[8:10] = array['p18',null,'p20'];
+select * from arrtest1;
+update arrtest1 set i[11:12] = array[null,22], t[11:12] = array[null,'p22'];
+select * from arrtest1;
+update arrtest1 set i[15:16] = array[null,26], t[15:16] = array[null,'p26'];
+select * from arrtest1;
+update arrtest1 set i[-5:-3] = array[-15,-14,-13], t[-5:-3] = array['m15','m14','m13'];
+select * from arrtest1;
+update arrtest1 set i[-7:-6] = array[-17,null], t[-7:-6] = array['m17',null];
+select * from arrtest1;
+update arrtest1 set i[-12:-10] = array[-22,null,-20], t[-12:-10] = array['m22',null,'m20'];
+select * from arrtest1;
+delete from arrtest1;
+insert into arrtest1 values(array[1,2,null,4], array['one','two',null,'four']);
+select * from arrtest1;
+update arrtest1 set i[0:5] = array[0,1,2,null,4,5], t[0:5] = array['z','p1','p2',null,'p4','p5'];
+select * from arrtest1;
+
 --
 -- array expressions and operators
 --